1. Field of the Invention
The present disclosure relates generally to a method for detaching material layers, and more particularly, to a method for detaching material layers of a semiconductor device.
2. Description of Related Art
A building block of many electronic devices such as diodes, transistors, and lasers is usually made of semiconductor material that can be grown over a substrate. The semiconductor material is fabricated by growing an epitaxial layer of the semiconductor material upon a substrate. For example, a light emitting diode (hereafter LED) is fabricated by growing an epitaxial layer of III-Nitride semiconductor on a sapphire substrate using a method of metal-organic chemical vapor deposition.
However, the sapphire substrate has a weak thermal conductivity, such that heat can not be dissipated efficiently out of the LED. This will reduce the light emitting efficiency of the LED. On the other hand, the sapphire substrate has a lattice parameter different from the III-Nitride semiconductor, thereby having a different expansion coefficient from the III-Nitride semiconductor. The difference of expansion coefficients may result in distortion of the sapphire substrate or the III-Nitride semiconductor when a temperature of the LED is high. Thus, the sapphire substrate is required to be detached/separated from the LED after growing epitaxial layer of III-Nitride semiconductor.
Typically, the sapphire substrate is detached from the LED by applying a method of laser lift off melt the epitaxial layer at its interface with the substrate on which is grown. However, the laser has high energy, which is absorbed by the epitaxial layer. This may break a lattice structure of the epitaxial layer, thereby resulting in quality reduction of the LED.
Therefore, there is a need in the art for method for detaching layers, which overcomes the above-mentioned problems.